What battery can be used as a standard voltage source?

Geo-TH,In · Dec 18, 2022

I don't remember what I used at Crane Naval base as a standard voltage source to calibrate their voltmeters with. Been over 50 years ago.
I think A mercury battery would make a good standard reliable voltage. The voltage during discharge remains practically constant at 1.35 volts.
Every battery I've used doesn't have a constant voltage. The voltage changes with age.
What would you consider a reliable voltage source to check a voltmeter's accuracy?

What do you use to make sure your voltmeters are accurate?
Yes, I have too much time on my hands now it's cold outside.
Please do your best to just answer my question and not rant about something else. Thank you.

MarkB_MI · Dec 18, 2022

A zener diode is a far better voltage reference than any battery.

John T · Dec 18, 2022

George, I retired as an EE from NSWC Crane and we used EXPENSIVE accurate electronic voltage sources never batteries of course.

You ask

1) I think A mercury battery would make a good standard reliable voltage. The voltage during discharge remains practically constant at 1.35 volts.

Of course the voltage changes based on the battery State of Charge SOC which changes according to load current and how much stored energy becomes depleted. The voltage sag of my Lithium Iron Phosphate LiFePo4
batteries is MUCH LESS then when I used Lead Acid.

2) What would you consider a reliable voltage source to check a voltmeter's accuracy?

An electronic source NOTTTTTTTTT a battery

The voltage of a Lithium Ion battery versus SOC is pictured below. As long as youre operating in the flat part of the curve such a battery (subject to load) is a decent source for a cheap albeit NOT perfect substitute for an electronic constant voltage source. Check it out

Hope this helps NOTE Im more experienced in AC Power Distribution than electronics so see what any more current ELECTRONIC Engineers have to say, but for now it looks like Lithium is a reasonable source for a fairly steady (subject to load and SOC) near constant voltage source at an affordable cost for your purposes...........

When will you be coming to Florida ????????????????????????

When will you be in the Leesburg and Eustis areas ???????

John T

Janicholson · Dec 18, 2022

I was about to post the same thing!. There are many possible circuits, here is a tutorial. Or you could purchase one!
Tutorial

Pre made unit

Geo-TH,In · Dec 18, 2022

January

Geo-TH,In · Dec 18, 2022

I was thinking of a zenor too.
Students would think if something else went we were on the topic of Zenor diodes.
I had to be careful and not say get out your zenor diode. I think the one I used was a 68 v zenor.
That would be perfect size.

jm. · Dec 18, 2022

Just had to rant about something else..LOl I barley can understand the question on all this electrical you are doing. but sure do love to read it and know there are smarter folks out there..

Geo-TH,In · Dec 18, 2022

Jerry,
No one has accused me of being smart. A woman working at the check out register at Krogers and asked if I wanted my milk in a bag. I said I preferred if she left it in the bottle, the bag may leak.
That's when I was called smart, a Smart A. I thanked her saying I like to be called a smart A instead of a dumb A.
It's become a running joke when she sees me at Krogers.

Electronics have been my hobby even when I was a kid.
After college I signed up for a correspondence course to repair radios and TVs back when TVs were tube. I love math and electronics is an example of applied math.

Geo-TH,In · Dec 18, 2022

JohnT
I don't think I can buy mercury batteries.
So I ordered this from Amazon;
Chanzon 30 Values 300pc 1W Zener Diode Assorted Kit (3V 3.3V 3.6V 3.9V 4.3V 4.7V 5.1V 5.6V 6.2V 6.8V 7.5V 8.2V 9.1V 10V 11V 12V 13V 15V 16V 18V 20V 22V 24V 27V 30V 33V 36V 39V 43V 47V) Assortment Set.

I plan to make a simple test circuit to calibrate my cheapie HF meters. I'll be surprised to see how the diodes work out.
I don't think I'll run out of zener diodes.

I may share a few with others. First I'll see how good they are.

Crazy Horse · Dec 18, 2022

It finally dawned on me what this is all about. OK George, I'll nominate you for a membership in MENSA. Now, lets get back to vintage tractors .....

John T · Dec 18, 2022

Sounds like fun George, let us know how things work out...I have some cheap HF quality meters plus a Fluke but my go to meter is my ancient Simpson 260 ANALOG

John T

JMOR · Dec 18, 2022

If you really want precision, forget simple Zeners and get a Temperature compensated reference diode 1N827. You can think of it as a high precision, specialized Zener if you like. You can compare a hundred of them & These will all be within a fraction of a percent or think millivolts. That will not be the case with a simple Zener diode.

Geo-TH,In · Dec 18, 2022

This is tractor related.
I'm trying to get new ballast and coil to match the same ballast and coil on my Jubilee. I want new parts for my son to use if he needs to repair my old Jubilee. I used my HF voltmeter to determine the ballast resistor I bought wasn't what it was supposed to be.
I want an accurate voltmeter to work on my old tractors.
I'm not convinced that spending more money is getting a better meter.

It finally dawned on me what this is all about.
You don't author many posts, instead you mostly rant.
Please author something about your tractors.

Geo-TH,In · Dec 18, 2022

Too Late Jessie. I have zenors in the mail as we speak.
Be interesting to see how the zenors stack up to each other.
Please tell us how you calibrate your meters.

caterpillar guy · Dec 18, 2022

Sounds like worrying about something that hasn't even happened yet and he will probably sell it if it needs worked on and buy something newer. For the amount of difference you are worrying about it is minuscule in the difference. To much time on your hands. Sounds like my dad worrying about cutting wood when he has a year or mores supply on hand.

JMOR · Dec 18, 2022

With 1N827 diode biased as per data sheet. For Ohms, I have an assortment of 0.25% precision resistors.

Crazy Horse · Dec 18, 2022

Sounds like you follow my posts pretty closely, nice to know that you're keeping track. As a few others have mentioned, you're making a complexity mountain out of a mole hill .

MarkB_MI · Dec 18, 2022

> Students would think if something else went we were on the topic of Zenor diodes. I had to be careful and not say get out your zenor diode.

Zener-weiner. Were these third graders? I can't imagine a high school student would think 'zener' was a funny word.

> I think the one I used was a 68 v zenor. That would be perfect size.

How would you bias a 68 volt zener? Did you have a 100 volt DC power supply? Or did you maybe mean a six-point-eight volt zener?

Janicholson · Dec 18, 2022

Did you look at my post just right here? much info. Jim

MarkB_MI · Dec 18, 2022

> Did you look at my post just right here? much info. Jim

Yes I did, Jim, and it's good information. This is the sort of stuff I did in a previous life.

Geo-TH,In · Dec 18, 2022

What does your post have to do with TRACTORS?

Jim in LA · Dec 19, 2022

When I took radio&tv repair in vo-tech school(77-80), I new hardly anything about algebra but picked it up quickly as it made sense to the application it was used for. Not like in school where they teach you math but not how it would be applied in the real world in a skilled trade. The availability of the modern scientific calculator at an affordable price made it so easy too. 1949 & 51 8N ..Tractor.

Crazy Horse · Dec 20, 2022

Sorry for the late reply George. I can't help you with your question, it wasn't my post. You'll have to ask the OP, I just replied to it. Before we put this thread to bed, a Merry Christmas to you and your family.

Texasmark · Dec 21, 2022

I have 4 or 5 of the used to be 5 dollar, HF voltmeters, a couple being 15 years old at least and yellow and a few of the newer red ones. All are within percentage points (containing gold band, metal oxide resistors or better) of each other and are accurate enough for my electrical measurements.....just allow 0.4 ohms for lead resistance when making resistance measurements since these aren't Simpson Analog Meters with the mirrored needle and Ohm zeroing rheostat.

What battery can be used as a standard voltage source?

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